Bearing Manufacturing

Table of Contents

Variety of Ball Bearings

The common material for bearing races is SAE 52100 Steel.
This alloy can withstand temperatures 250 degrees F or greater depending on how to steel was heat treated.
The steel is also very elastic, good for machining and has good uniformity properties.
This material is also commonly used for ball bearings.AISI 440C

Also, a popular choice of alloy is AISI 440C Stainless steel, due to its anti-corrosive properties.
440C Steel is more expensive than SAE 52100 Steel and has a lower load capacity.

Used in critical life support systems due to the high reliability and high strength.
M50 steel is stronger than 52100 steel due to molybdenum added to the alloy. This however makes M50 steel much more expensive than 52100 steel.

SAE 52100 Steel

The bearings come to the factory as as tube stock and are fed into machines that cut the metal into the general shape of the rings leaving extra material for future machining. After this step the outer ring of the bearing is stamped with the bearing number and manufacturing information.
In order to withstand the heavy loads put onto the bearing, the bearings needs to go through a hardening process. The bearings are heated to 850 degrees Celsius then quenched in oil. After the quenching the metal is then tempered between150 to 200 degrees Celsius.
Next the inner and outer rings get grinded into there final shape. The rings are set on a lathe where the race ways are ground, and the bore and the side face or the side face and the outer face are made perpendicular. At this step the race ways are polished and made smooth.

Bearing Raceway Grinding

Steel wires are die cut into a general ball shape where the then go into a drum where they are continuously tumbling until the are filed smooth.
After tumbling the ball bearings get polished to a mirror like finish and then are checked to ensure roundness. Once round the bearings are then heat treated similarly to the inner and outer rings.
Balls then are sorted to within 0.001mm and distributed.

Ball Bearing Die Cutting

Each bearing has a specific internal clearance that has been set for a certain application. To meet a specific internal clearance the bearings inner and outer raceways are measured and a computer picks the proper size and amount of rolling element to insert into bearing. This process is specific to each matching pair of inner and outer ring.
Next the retainer is added to both sides of the bearing and is sent to be cleaned before being greased.
After being greased the bearings seal is added and is ready to be inspected.
At this stage bearings will be tested for sound, durability, precision and performance. If the tests are passed the bearing are ready to be sold.

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